@catlabtech/webcvt-image-heic

HEIC / HEIF decode backend for webcvt, wrapping libheif-js (libheif in WebAssembly).

Convert iPhone/iPad photos (.heic, .heif) to PNG / JPEG / WebP entirely in the browser — no upload, no server. Decode-only: libheif-js ships a decoder but no encoder, so there is no HEIC output.

Installation

npm i @catlabtech/webcvt-image-heic libheif-js

libheif-js is an optional peer dependency — installing it is explicit.

Supported conversions

Input	Output
HEIC, HEIF	JPEG, PNG, WebP

All paths decode with libheif (wasm) and re-encode through a canvas pixel-bridge, so they need OffscreenCanvas (browsers, workers). In Node without a canvas, use the lower-level decodeHeic() to get raw ImageData.

Usage

import { registerHeicBackend } from '@catlabtech/webcvt-image-heic';

// Opt-in registration — no wasm is loaded until the first conversion.
registerHeicBackend();

Then call convert() from @catlabtech/webcvt-core as usual; the HEIC backend is selected automatically for the pairs above. Lower-level decodeHeic / imageDataToBlob free functions are also exported.

import { decodeHeic, imageDataToBlob } from '@catlabtech/webcvt-image-heic';

const imageData = await decodeHeic(heicBytes);          // → ImageData (RGBA)
const jpeg = await imageDataToBlob(imageData, 'image/jpeg', 0.85);

Notes

• The libheif-js/wasm-bundle entry inlines the wasm as base64 (no separate .wasm fetch), so it works under a strict CSP and offline. It needs script-src 'wasm-unsafe-eval'.
• Only the primary image of a HEIC is decoded — bursts / image sequences, depth maps, and auxiliary images are out of scope for v1.
• Security caps: 256 MiB max input, 40 MP max image (typed errors on violation).

Source

packages/image-heic/src